In the field of reconstructive surgery, tissue expanders play an important role. Mechanical tissue expansion is a means to increase the dimensions of tissue. The technique is commonly used in surgery involving the implantation of permanent prosthetics, such as breast reconstruction, and reconstructive surgery in which additional skin is required, such as burn reconstruction.
Tissue expansion for cosmetic or reconstructive surgery has two components: dissection of the skin and subdermal elements from the underlying tissue, to create a cavity, and expansion of an expander device placed in the cavity to stretch the surrounding tissues, particularly the skin. The dissection process may continue after implantation of an expander, thus recruiting additional tissue to stretch in response to the force of the expander.
The expansion of tissue can be a painful procedure, require long time periods, or both. Furthermore, the success of a tissue expansion procedure will depend on the characteristics of the individual's skin, e.g., whether it is elastic and pliable, youthful, and other factors. Tissue expansion is based on the principle that skin and subdermal elements, including nervous tissue and vascular structures, stretch in response to expansion of an enlarging mass. The stretching results in an increase in surface area of the skin and other tissues. However, prior to the instant invention, there has been no concurrent pharmacological component of tissue expansion devices.
U.S. Pat. No. 2,499,045 to Walker et al., relates to an ano-rectal dilator and medicator. The invention consists of a tube with apertures, which is connected to an air inflation device, a bladder element enclosing the apertured portion of the tube, a non-expandable fabric form element that defines a maximum expansion size surrounding the bladder element, and a perforated resilient casing element surrounding the form element. A quantity of a treating agent can be interposed between the form element and the perforated casing element so that when the device is inflated, the treating agent is forced outwardly through the perforations and into contact with the affected areas of the rectal passage. The device does not include a chamber for holding the treatment agent, nor does it provide for replacing treating agent in situ.
U.S. Pat. No. 3,934,274 to Hartley, Jr., relates to a surgically implantable tissue augmentation prosthesis for mammary augmentation. The device comprises an outer sac and an inner capsule which is contained within the outer sac and occupies less than the entire volume of the outer sac. A gel or liquid is sealed within the inner capsule. The outer sac is filled with a liquid using a filling valve. Liquid in the outer sac may be withdrawn in order to deflate the prosthesis in response to spherical contracture.
U.S. Pat. No. 4,685,447 to Iversen et al., relates to a tissue expander system including a flat one-piece molded tissue expander, a connecting tube, and an injection port. A piece of non-stick fluorocarbon material can be used to prevent sticking of the tissue expander material during expansion. A Dacron mesh can be embedded in the tissue expander to provide for directional expansion.
U.S. Pat. No. 4,800,901 to Rosenberg, relates to a balloon type tissue expander which is inflated through a tube connected to the balloon and extending through an opening in the skin. In addition, there is a separate drain tube attached to or surrounding the inflation tube. The drain tube allows fluid, which may accumulate at the implantation site, to exit through an opening in the skin. An irrigation tube which is connected to the drain tube or inside the drain tube may also be included. This permits an irrigating liquid to be introduced into the implantation site of the balloon.
U.S. Pat. No. 4,984,585 to Austad, relates to a tissue expander comprised of an inflatable envelope, which can be separably mounted on a more rigid base, and a connector tube system which introduces fluid into the envelope. This invention provides for cutting the base into any desired shape, and conforming the expandable envelope to that shape.
U.S. Pat. No. 5,005,591 to Austad, relates to a self-inflating tissue expander. The tissue expander has a window portion which is highly permeable to extracellular water, however, the remaining portion is generally impermeable to water. The expander contains an osmotic agent that absorbs extracellular water. Absorption of water causes inflation of the implant.
Adjunctive Agents to Facilitate Rapid Tissue Expansion by Netscher et al. (Ann. Plast. Surg. 23:412, 1989), relates to a study of the effects of hyaluronidase, colchicine and prostaglandin E.sub.2 on tissue expansion using rodent models. The agents were delivered into the tissue surrounding the implanted tissue expander by use of an intravenous catheter mounted on the circumference of the tissue expander. Infusion of a chemical agent was entirely independent of the expansion process.
The citation of any reference herein should not be deemed an admission that such reference is available as prior art to the invention.